UCB= rs-type or (2-12) standard form UCB= rx-type or (2-12) execute form

Specifies the address of the UCB for the VTOC to be accessed. The UCB address can be for a captured UCB, or for an actual UCB above or below the 16MB line. Use the address of a UCB, not a UCB copy. An unauthorized caller must not use this parameter. If your program is in 31-bit mode, this address must be in 31-bit address; the high order byte is part of the address. You should not code the UCB parameter with MF=L.

Recommendations::

• Code the address of the UCB parameter only as register (2-12). Coding an RX-type address gives you unpredictable results.
• Do not use the UCB address passed back in the CVPL from a previous CVAFSEQ request, particularly in AMODE=24, as it may be invalid (because it is a captured and then uncaptured address). The recommendation is to use IOAREA=KEEP.

DEB=addr

Supplies the address of a DEB opened to the VTOC you want to access. CVAF does not allow output requests to the VTOC or VTOC index if you specify the DEB subparameter. If you are not authorized, you cannot perform any asynchronous activity (such as EXCP, CLOSE, EOV), against the data set represented by the DEB because CVAF removes the DEB from the DEB table for the duration of the CVAF call. If you are not authorized (neither APF authorized nor in a system key), specify a DEB address, not a UCB, to CVAFSEQ. See Identifying the Volume for further details.

If you supply a previously obtained I/O area through the IOAREA keyword, neither UCB nor DEB need be supplied. Otherwise, supply either a UCB or DEB. If you supply a UCB address, it is overlaid in the CVPL by the UCB address in the I/O area. If you supply both the UCB and the DEB addresses in the CVPL, the DEB address is used and the UCB address in the CVPL is overlaid by the UCB address in the DEB.